Inbred corn line PHP55

ABSTRACT

According to the invention, there is provided an inbred corn line, designated PHP55. This invention thus relates to the plants and seeds of inbred corn line PHP55 and to methods for producing a corn plant produced by crossing the inbred line PHP55 with itself or with another corn plant. This invention further relates to hybrid corn seeds and plants produced by crossing the inbred line PHP55 with another corn line or plant and to crosses with related species.

FIELD OF THE INVENTION

This invention is in the field of corn breeding, specifically relating to an inbred corn line designated PHP55.

BACKGROUND OF THE INVENTION

The goal of plant breeding is to combine in a single variety/hybrid various desirable traits. For field crops, these traits may include resistance to diseases and insects, tolerance to heat and drought, reducing the time to crop maturity, greater yield, and better agronomic quality. With mechanical harvesting of many crops, uniformity of plant characteristics such as germination and stand establishment, growth rate, maturity, and fruit size, is important.

Field crops are bred through techniques that take advantage of the plant's method of pollination. A plant is self-pollinated if pollen from one flower is transferred to the same or another flower of the same plant. A plant is cross-pollinated if the pollen comes from a flower on a different plant.

Plants that have been self-pollinated and selected for type for many generations become homozygous at almost all gene loci and produce a uniform population of true breeding progeny. A cross between two homozygous lines produce a uniform population of hybrid plants that may be heterozygous for many gene loci. A cross of two plants each heterozygous at a number of gene loci will produce a population of hybrid plants that differ genetically and will not be uniform. Corn plants (Zea mays L.) can be bred by both self-pollination and cross-pollination techniques. Corn has separate male and female flowers on the same plant, located on the tassel and the ear, respectively. Natural pollination occurs in corn when wind blows pollen from the tassels to the silks that protrude from the tops of the incipient ears.

The development of corn hybrids requires the development of homozygous inbred lines, the crossing of these lines, and the evaluation of the crosses. Pedigree breeding and recurrent selection breeding methods are used to develop inbred lines from breeding populations. Breeding programs combine the genetic backgrounds from two or more inbred lines or various other broad-based sources into breeding pools from which new inbred lines are developed by selfing and selection of desired phenotypes. The new inbreds are crossed with other inbred lines and the hybrids from these crosses are evaluated to determine which of those have commercial potential.

Pedigree breeding for single-gene traits starts with the crossing of two genotypes, each of which may have one or more desirable characteristics that is lacking in the other or which complement the other. If the two original parents do not provide all of the desired characteristics, other sources can be included in the breeding population. In the pedigree method, superior plants are selfed and selected in successive generations. In the succeeding generations the heterozygous condition gives way to homogeneous lines as a result of self-pollination and selection. Typically in the pedigree method of breeding five or more generations of selfing and selection is practiced: F₁ →F₂ ; F₂ →F₃ ; F₃ →F₄ ; F₄ →F₅, etc.

Backcrossing can be used to improve an inbred line. Backcrossing transfers a specific desirable trait from one inbred or source to an inbred that lacks that trait. This can be accomplished for example by first crossing a superior inbred (A) (recurrent parent) to a donor inbred (non-recurrent parent), which carries the appropriate gene(s) for the trait in question. The progeny of this cross is then mated back to the superior recurrent parent (A) followed by selection in the resultant progeny for the desired trait to be transferred from the non-recurrent parent. After five or more backcross generations with selection for the desired trait, the progeny will be heterozygous for loci controlling the characteristic being transferred, but will be like the superior parent for most or almost all other genes. The last backcross generation would be selfed to give pure breeding progeny for the gene(s) being transferred.

A single cross hybrid corn variety is the cross of two inbred lines, each of which has a genotype which complements the genotype of the other. The hybrid progeny of the first generation is designated F₁. In the development of hybrids only the F₁ hybrid plants are sought. Preferred F₁ hybrids are more vigorous than their inbred parents. This hybrid vigor, or heterosis, can be manifested in many polygenic traits, including increased vegetative growth and increased yield.

The development of a hybrid corn variety involves three steps: (1) the selection of plants from various germplasm pools; (2) the selfing of the selected plants for several generations to produce a series of inbred lines, which, although different from each other, each breed true and are highly uniform; and (3) crossing the selected inbred lines with unrelated inbred lines to produce the hybrid progeny (F₁). During the inbreeding process in corn, the vigor of the lines decreases. Vigor is restored when two unrelated inbred lines are crossed to produce the hybrid progeny (F₁). An important consequence of the homozygosity and homogeneity of the inbred lines is that the hybrid between any two inbreds will always be the same. Once the inbreds that give a superior hybrid have been identified, the hybrid seed can be reproduced indefinitely as long as the homogeneity of the inbred parents is maintained.

A single cross hybrid is produced when two inbred lines are crossed to produce the F₁ progeny. A double cross hybrid is produced from four inbred lines crossed in pairs (A×B and C×D) and then the two F₁ hybrids are crossed again (A×B)×(C×D). Much of the hybrid vigor exhibited by F₁ hybrids is lost in the next generation (F₂). Consequently, seed from hybrid varieties is not used for planting stock.

Corn is an important and valuable field crop. Thus, a continuing goal of plant breeders is to develop high-yielding corn hybrids that are agronomically sound based on stable inbred lines. The reasons for this goal are obvious: to maximize the amount of grain produced with the inputs used and minimize susceptibility to environmental stresses. To accomplish this goal, the corn breeder must select and develop superior inbred parental lines for producing hybrids. This requires identification and selection of genetically unique individuals which in a segregating population occur as the result of a combination of crossover events plus the independent assortment of specific combinations of alleles at many gene loci which results in specific genotypes. Based on the number of segregating genes, the frequency of occurrence of an individual with a specific genotype is less than 1 in 10,000. Thus, even if the entire genotype of the parents has been characterized and the desired genotype is known, only a few if any individuals having the desired genotype may be found in a large F₂ or S₀ population. Typically, however, the genotype of neither the parents nor the desired genotype is known in any detail.

SUMMARY OF THE INVENTION

According to the invention, there is provided a novel inbred corn line, designated PHP55. This invention thus relates to the seeds of inbred corn line PHP55, to the plants of inbred corn line PHP55, and to methods for producing a corn plant produced by crossing the inbred line PHP55 with itself or another corn line. This invention further relates to hybrid corn seeds and plants produced by crossing the inbred line PHP55 with another corn line or a related species.

DEFINITIONS

In the description and examples that follow, a number of terms are used herein. In order to provide a clear and consistent understanding of the specification and claims, including the scope to be given such terms, the following definitions are provided:

BAR PLT=BARREN PLANTS. This is the number of plants per plot that were not barren (lack ears).

BRT STK=BRITTLE STALKS. This is a measure of the stalk breakage near the time of pollination, and is an indication of whether a hybrid or inbred would snap or break near the time of flowering under severe winds. Data are presented as percentage of plants that did not snap.

BU ACR=YIELD (BU$HELS/ACRE). Actual yield of the grain at harvest adjusted to 15.5% moisture. ABS is in absolute terms and % MN is percent of the mean for the experiments in which the inbred or hybrid was grown.

CLD TST=COLD TEST. This is the percentage of kernels that germinate under cold soil conditions. ABS ™absolute measurement and % MN is percentage of mean of the experiments in which inbred or hybrid was grown.

COB SC=COB SCORE. The cob score is a rating of how well the grain is shelled off the cob and how badly the cob is broken up going through the combine This is given as a 1 to 9 score with 9 being very good. A high score indicates that the grain shells off of the cob well, and the cob does not break.

DRP EAR=DROPPED EARS. This is a measure of the number of dropped ears per plot and represents the percentage of plants that did not drop ears prior to harvest.

EAR HT=EAR HEIGHT. The ear height is a measure from the ground to the top developed ear node attachment and is measured in inches.

EAR SZ=EAR SIZE. A 1 to 9 visual rating of ear size. The higher the rating the larger the ear size.

EST CNT=EARLY STAND COUNT. This is a measure of the stand establishment in the spring and represents the number of plants that emerge on a per plot basis for the inbred or hybrid.

GDU SHD=GDU TO SHED. The number of growing degree units (GDUs) or heat units required for an inbred line or hybrid to have approximately 50 percent of the plants shedding pollen and is measured from the time of planting. Growing degree units are calculated by the Barger Method, where the heat units for a 24-hour period are: ##EQU1##

The highest maximum temperature used is 86° F. and the lowest minimum temperature used is 50° F. For each inbred or hybrid it takes a certain number of GDUs to reach various stages of plant development.

GDU SLK=GDU TO SILK. The number of growing degree units required for an inbred line or hybrid to have approximately 50 percent of the plants with silk emergence from time of planting. Growing degree units are calculated by the Barger Method as given in GDU SHD definition.

GRN QUL=GRAIN QUALITY. This is a 1 to 9 rating for the general quality of the shelled grain as it is harvested based on such factors as the color of the harvested grain, any mold on the grain, and any cracked grain. High scores indicate good grain quality.

KER LB=KERNELS PER POUND. This is the number of kernels per 0.1 pound.

KSZ L=KERNEL SIZE LARGE. Percentage by weight of shelled corn that passes through a screen with 25/64 inch diameter openings but does not pass through a screen with 22/64 inch diameter openings.

KSZ MF=KERNEL SIZE MEDIUM FLAT. Percentage by weight of shelled corn that passes through a screen with 22/64 inch diameter openings and a screen with 13/64 inch wide slot screen but does not pass through a screen with 18.5/64 inch diameter openings.

KSZ MR=KERNEL SIZE MEDIUM ROUND. Percentage by weight of shelled corn that passes through a screen with 22/64 inch diameter openings but does not pass through a 13/64 inch wide slot screen or a screen with 18.5/64 inch diameter openings.

KSZ S=KERNEL SIZE SMALL. Percentage by weight of shelled corn that passes through a screen with 18.5/64 inch diameter openings but does not pass through a screen with 16/64 inch diameter openings.

KSZ TIP=KERNEL SIZE TIPS. Percentage by weight of shelled corn that passes through a screen with 16/64 inch diameter openings.

KSZ XL=KERNEL SIZE EXTRA LARGE. Percentage by weight of shelled corn that does not pass through a screen with 25/64 inch diameter openings.

MST=HARVEST MOISTURE. The moisture is the actual percentage moisture of the grain at harvest.

PLT HT=PLANT HEIGHT. This is a measure of the height of the plant from the ground to the tip of the tassel in inches.

POL WT=POLLEN WEIGHT. This is the weight of pollen per 100 plants taken on a plot basis. ABS refers to data in absolute, and % MN refers to data presented as percentage of experimental mean.

PRM=PREDICTED RM. This trait, predicted relative maturity (RM), is based on the harvest moisture of the grain. The relative maturity rating is based on a known set of checks and utilizes standard linear regression analyses and is referred to as the Minnesota Relative Maturity Rating System.

RT LDG=ROOT LODGING. Root lodging is the percentage of plants that do not root lodge; plants that lean from the vertical axis at an approximately 30° angle or greater would be counted as root lodged.

SCT GRN=SCATTER GRAIN. A 1 to 9 visual rating indicating the amount of scatter grain (lack of pollination or kernel abortion) on the ear. The higher the score the less scatter grain.

SDG VGR=SEEDLING VIGOR. This is the visual rating (1 to 9) of the amount of vegetative growth after emergence at the seedling stage (approximately five leaves). A higher score indicates better vigor.

SEL lND=SELECTION INDEX. The selection index gives a single measure of the hybrid's worth based on information for up to five traits. A corn breeder may utilize his or her own set of traits for the selection index. One of the traits that is almost always included is yield. The selection index data presented in the tables represent the mean value averaged across testing stations.

STA GRN=STAY GREEN. Stay green is the measure of plant health near the time of black layer formation (physiological maturity). A high score indicates better late-season plant health.

STK CNT=NUMBER OF PLANTS. This is the final stand or number of plants per plot.

STK LDG=STALK LODGING. This is the percentage of plants that did not stalk lodge (stalk breakage) as measured by either natural lodging or pushing the stalks and determining the percentage of plants that break below the ear.

TAS BLS=TASSEL BLAST. A 1 to 9 visual rating was used to measure the degree of blasting (necrosis due to heat stress) of the tassel at time of flowering. A 1 would indicate a very high level of blasting at time of flowering, while a 9 would have no tassel blasting.

TAS SZ=TASSEL SIZE. A 1 to 9 visual rating was used to indicate the relative size of the tassel. The higher the rating the larger the tassel.

TAS WT=TASSEL WEIGHT. This is the average weight of a tassel (grams) just prior to pollen shed.

TEX EAR=EAR TEXTURE. A 1 to 9 visual rating was used to indicate the relative hardness (smoothness of crown) of mature grain. A 1 would be very soft (extreme dent) while a 9 would be very hard (flinty or very smooth crown).

TILLER=TILLERS. A count of the number of tillers per plot that could possibly shed pollen was taken. Data is given as percentage of tillers: number of tillers per plot divided by number of plants per plot.

TST WT=TEST WEIGHT UNADJUSTED. The measure of the weight of the grain in pounds for a given volume (bushel).

TST WTA=TEST WEIGHT ADJUSTED. The measure of the weight of the grain in pounds for a given volume (bushel) adjusted for percent moisture.

YLD=YIELD. It is the same as BU ACR ABS.

YLD SC=YIELD SCORE. A 1 to 9 visual rating was used to give a relative rating for yield based on plot ear piles. The higher the rating the greater visual yield appearance.

CLN=Corn Lethal Necrosis (MCMV™Maize Chlorotic Mottle Virus and MDMV™Maize Dwarf Mosaic Virus): Visual rating (1-9 score) where a "1" is very susceptible and a "9" is very resistant.

MDM CPX=Maize Dwarf Mosaic Complex (MDMV™Maize Dwarf Mosaic Virus & MCDV=Maize Chlorotic Dwarf Virus): Visual rating (1-9 score) where a "1" is very susceptible and a "9" is very resistant.

COM SMT=Common Smut (Ustilago maydis): Percentage of plants that did not have infection.

ANT ROT=Anthracnose Stalk Rot (Colletotrichum graminicola): Visual rating (1-9 score) where a "1" is very susceptible and a "9" is very resistant.

SLF BLT=Southern Leaf Blight (Bipolaris maydis, Helminthosporium maydis): Visual rating (1-9 score) where a "1" is very susceptible and a "9" is very resistant.

NLF BLT=Northern Leaf Blight (Exserohilum turcicum, H. turcicum): Visual rating (1-9 score) where a "1" is very susceptible and a "9" is very resistant.

HC BLT=Helminthosporium Carbonum Leaf Blight (Bipolariszeicola, H. carbonum): Visual rating (1-9 score) where a "1" is very susceptible and a "9" is very resistant.

COM RST=Common Rust (Puccinia sorghi): Visual rating (1-9 score) where a "1" is very susceptible and a "9" is very resistant.

SO RST=Southern Rust (Puccinia polysora): Visual rating (1-9 score) where a "1" is very susceptible and a "9" is very resistant.

EYE SPT=Eyespot (Kabatiella zeae): Visual rating (1-9 score) where a "1" is very susceptible and a "9" is very resistant.

GLF SPT=Gray Leaf Spot (Cercospora zeae-maydis): visual rating (1-9 score) where a "1" is very susceptible and a "9" is very resistant.

STW WLT=Stewart's Wilt (Erwinia stewartii): Visual rating (1-9 score) where a "1" is very susceptible and a "9" is very resistant.

GOS WLT=Goss's Wilt (Corynebacterium nebraskense): Visual rating (1-9 score) where a "1" is very susceptible and a "9" is very resistant.

HD SMT=Head Smut (Spacelotheca reiliana): Percentage of plants that did not have infection.

DNY MIL=Downy Mildew (Peronosclerospora sorghi): Percentage of plants that did not have infection.

FUS EAR=Fusarium Ear Mold (Fusarium moniliforme): Percentage of plants that did not have infection.

EAR MLD=General Ear Mold: Visual rating (1-9 score) where a "1" is very susceptible and a "9" is very resistant. This is based on overall rating for ear mold of mature ears without determining specific mold organism, and may not be predictive for a specific ear mold.

ECB DPE Dropped ears due to European Corn Borer (Ostrinia nubilalis): Percentage of plants that did not drop ears under second brood corn borer infestation.

ECB 2SC=European Corn Borer Second Brood (Ostrinia nubilalis): Visual rating (1-9 score) of post flowering damage due to infestation by European Corn Borer. A "1" is very susceptible and a "9" is very resistant.

ECB lLF=European Corn Borer First Brood (Ostrinia nubilalis): Visual rating (1-9 score) of pre-flowering leaf feeding by European Corn Borer. A "1" is very susceptible and a "9" is very resistant.

ECB 2IT=European Corn Borer Second Brood Tunneling (Ostrinia nubilalis): The average inches of tunneling in the stalk due to second brood (post-flowering) European Corn Borer infestation. Determined by splitting stalks with a knife, from four internodes above the ear to the ground.

DETAILED DESCRIPTION OF THE INVENTION

Inbred Corn Line PHP55 is a yellow, dent corn inbred with superior characteristics and provides an excellent female parental line in crosses for producing first generation F₁ corn hybrids. This inbred is best adapted over the Northern region of the United States. The inbred can be used to produce hybrids from approximately 100-117 relative maturity based on the Minnesota Relative Maturity Rating System for harvest moisture of grain. Because of its excellent yielding ability, adequate cold test scores and good sizing, PHP55 is best used as a female parent. PHP55 is not acceptable as a male parent because of its marginal pollen yield. PHP55 was only 66% of the experimental mean for amount of pollen in the pollen yield test averaged over 7 locations.

The inbred has shown uniformity and stability within the limits of environmental influence for all the traits as described in the Variety Description Information (Table 1) that follows. Most of the data in the Variety Description Information was collected at Johnston, Iowa. The inbred has been self-pollinated and ear-rowed a sufficient number of generations with careful attention paid to uniformity of plant type to ensure homozygosity and phenotypic stability. The line has been increased both by hand and in isolated fields with continued observation for uniformity. No variant traits have been observed or are expected in PHP55.

Inbred corn line PHP55, being substantially homozygous, can be reproduced by planting seeds of the line, growing the resulting corn plants under self-pollinating or sib-pollinating conditions with adequate isolation, and harvesting the resulting seed, using techniques familiar to the agricultural arts.

                  TABLE 1                                                          ______________________________________                                         PHP55                                                                          VARIETY DESCRIPTION INFORMATION                                                ______________________________________                                         Type: Dent      Region Best Adapted: North                                     A.  Maturity: Average of Northern maturity zone. Zone: 2                       INBRED =     PHP55                                                             Heat Unit Shed:                                                                             1430                                                              Heat Unit Silk:                                                                             1480                                                              No. Reps:    25                                                                HEAT UNITS =                                                                    ##STR1##                                                                      B.  Plant Characteristics:                                                         Plant height (to tassel tip): 203 cm                                           Length of top ear internode: 14 cm                                             Number of ears per stalk: Single with slight two-ear                           tendency                                                                       Ear height (to base of top ear): 85 cm                                         Number of tillers: None                                                        Cytoplasm type: Normal                                                     C.  Leaf:                                                                          Color: (B14) Dark Green                                                        Angle from Stalk: 30-60 degrees                                                Marginal Waves: (OH7L) Many                                                    Number of Leaves (mature plants): 19                                           Sheath Pubescence: (W22) Light                                                 Longitudinal Creases: (PA11) Many                                              Length (Ear node leaf): 75 cm                                                  Width (widest point, ear node leaf): 9 cm                                  D.  Tassel:                                                                        Number lateral branches: 17                                                    Branch Angle from central spike: 30-40 degrees                                 Pollen Shed: Light based on pollen Yield Test (66% of                          experiment mean).                                                              Peduncle Length (top leaf to basal branches): 24 gm                            Another Color: Yellow                                                          Glume Color: Green                                                         E.  Ear (Husked Ear Data Except When Stated Otherwise):                            Length: 16 cm                                                                  Weight: 101 gm                                                                 Mid-point Diameter: 42 m                                                       Silk Color: Pinkish-yellow                                                     Husk Extension (Harvest stage): Medium (barely covering                        ear)                                                                           Husk Leaf: Long (>15 cm)                                                       Taper of Ear: Average taper                                                    Position of Shank (dry husks): Drooping                                        Kernel Rows: Straight, Distinct, Number = 14                                   Husk Color (fresh): Light green                                                Husk Color (dry): Buff                                                         Shank Length: 11cm                                                             Shank (No. of internodes): 7                                               F.  Kernel (Dried):                                                                Size (from ear mid-point)                                                      Length: 11 mm                                                                  Width:  9 mm                                                                   Thick:  5 mm                                                                   Shape Grade (% rounds): 20-40% medium rounds based on                          Parent Test                                                                    Pericarp Color: Colorless                                                      Aleurone Color: Homozygous yellow                                              Endosperm Color: Yellow                                                        Endosperm Type: Normal                                                         Gm Wt/100 Seeds (unsized): 24 gm                                           G.  Cob:                                                                           Diameter at mid-point: 26 mm                                                   Strength: Strong                                                               Color: Red                                                                 H.  Diseases:                                                                      Corn Lethal Necrosis (MCMV = Maize Chlorotic                                   Mottle Virus and MDMV = Maize Dwarf                                            Mosaic Virus): Susceptible                                                     Maize Dwarf Mosaic Complex (MDMV &                                             MCDV = Maize Chlorotic Dwarf                                                   Virus): Susceptible                                                            Anthracnose Stalk Rot (C. Graminicola): Susceptible                            S. Leaf Blight (H. Maydis): Intermediate                                       N. Leaf Blight (H. Turcicum): Intermediate                                     Carbonum Leaf Blight (H. Carbonum): Intermediate                               Common Rust (P. Sorghi): Intermediate                                          Eye Spot (K. Zeae): Susceptible                                                Gray Leaf Spot (C. Zeae): Susceptible                                          Stewarts Wilt (E. Stewartii): Intermediate                                     Goss's Wilt (C. Nebraskense): Intermediate                                     Common Smut (U. Maydis): Resistant                                             Head Smut (S. Reiliana): Intermediate                                          Downy Mildew (S. Sorghi): Resistant                                            Fusarium Ear Mold (F. Moniliforme): Susceptible                            I.  Insects:                                                                       European Corn Borer-1 Leaf Damage (Pre-flowering):                             Intermediate                                                                   European Corn Borer-2 (Post-flowering): Susceptible                        J.  Variety Most Closely Resembling:                                           Character  Indred                                                              Maturity   PHG29                                                               Usage      PHG29                                                               ______________________________________                                          *If maximum is greater than 86 degrees fahrenheit, then 86 is used and if      minimum is less than 50, then 50, is used. Heat units accumulated daily        and can not be less than 0.                                              

PHG29 (PVP Certificate No. 8600047) is a Pioneer Hi-Bred International, Inc. proprietary inbred.

Data for items B, C, D, E, F, and G are based primarily on a maximum of three reps of data from Johnston, Iowa grown in 1987 and 1988, plus description information from the maintaining station.

                  TABLE 2                                                          ______________________________________                                         ELECTROPHORESIS RESULTS                                                        Isozyme Genotypes for PHP55                                                    Isozyme data was generated for inbred corn line PHP55                          according to the procedure described in Goodman, M. M. and                     Stuber, C. M., "Genetic identification of lines and crosses                    using isoenzyme electrophoresis," Proceedings of the Thirty-                   Fifth Annual Corn and Sorghum Industry Research Conference,                    Chicago, Illinois (1980).                                                      Alleles Present                                                                ______________________________________                                                 Loci  PHP55                                                            ______________________________________                                                 ACP1  2                                                                        ADH1  4                                                                        CAT3  9                                                                        DIA1  8                                                                        GOT1  4                                                                        GOT2  4                                                                        GOT3  4                                                                        IDH1  4                                                                        IDH2  6                                                                        MDH1  6                                                                        MDH2  3.5                                                                      MDH3  16                                                                       MDH4  12                                                                       MDH5  12                                                                       MMM   4                                                                        PGM1  9                                                                        PGM2  4                                                                        PGD1  3.8                                                                      PGD2  5                                                                        PHI1  4                                                                ______________________________________                                    

INDUSTRIAL APPLICABILITY

This invention also is directed to methods for producing a corn plant by crossing a first parent corn plant with a second parent corn plant wherein the first or second parent corn plant is an inbred corn plant from the line PHP55. Further, both first and second parent corn plants can come from the inbred corn line PHP55. Thus, any such methods using the inbred corn line PHP55 are part of this invention: selfing, backcrosses, hybrid production, crosses to populations, and the like. All plants produced using inbred corn line PHP55 as a parent are within the scope of this invention. Advantageously, the inbred corn line is used in crosses with other, different, corn inbreds to produce first generation (F₁) corn hybrid seeds and plants with superior characteristics.

As used herein, the terms "plant and plant parts" include plant cells, plant protoplasts, plant cell tissue culture from which corn plants can be regenerated, plant calli, plant clumps, and plant cells that are intact in plants or parts of plants, such as embryos, pollen, flowers, kernels, ears, cobs, leaves, husks, stalks, roots, root tips, anthers, silk and the like.

Tissue culture of corn is described in European Patent Application, publication 160,390, incorporated herein by reference. Corn tissue culture procedures are also described in Green and Rhodes, "Plant Regeneration in Tissue Culture of Maize," Maize for Biological Research (Plant Molecular Biology Association, Charlottsville, Virginia 1982, at 367-372. Thus, another aspect of this invention is to provide cells which upon growth and differentiation produce the inbred line PHP55.

The utility of inbred line PHP55 also extends to crosses with other species. Commonly, suitable species will be of the family Graminaceae, and especially of the genera Zea, Tripsacum, Coix, Schlerachne, Polytoca, Chionachne, and Trilobachne, of the tribe Maydeae. Of these, Zea and Tripsacum, are most preferred. Potentially suitable for crosses with PHP55 may be the various varieties of grain sorghum, Sorghum bicolor (L.) Moench.

Corn is used as human food, livestock feed, and as raw material in industry. The food uses of corn, in addition to human consumption of corn kernels, include both products of dry- and wet-milling industries. The principal products of corn dry milling are grits, meal and flour. The corn wet-milling industry can provide corn starch, corn syrups, and dextrose for food use. Corn oil is recovered from corn germ, which is a by-product of both dry- and wet-milling industries.

Corn, including both grain and non-grain portions of the plant, is also used extensively as livestock feed, primarily for beef cattle, dairy cattle, hogs, and poultry.

Industrial uses of corn are mainly from corn starch from the wet-milling industry and corn flour from the dry-milling industry. The industrial applications of corn starch and flour are based on functional properties, such as viscosity, film formation, adhesive properties, and ability to suspend particles. The corn starch and flour have application in the paper and textile industries. Other industrial uses include applications in adhesives, building materials, foundry binders, laundry starches, explosives, oil-well muds, and other mining applications.

Plant parts other than the grain of corn are also used in industry. Stalks and husks are made into paper and wallboard and cobs are used for fuel and to make charcoal.

The seed of inbred corn line PHP55, the plant produced from the inbred seed, the hybrid corn plant produced from the crossing of the inbred, hybrid seed, and various parts of the hybrid corn plant can be utilized for human food, livestock feed, and as a raw material in industry.

EXAMPLE Inbred and Hydrid Performance of PHP55

In the examples that follow the traits and characteristics of inbred corn line PHP55 are given as a line and in hybrid combination. The data collected on inbred corn line PHP55 is presented for the key characteristics and traits.

The results in Table 3 compare PHP55 to PHG29. PHG29 (PVP Certificate #8600047) is an important inbred that would be used in the area that PHP55 would be used and would cross well with many of the same inbred lines. This data has been collected from three years of research testing. The results show that the two lines differ significantly for a number of traits. PHP55 is larger eared, is later to flower, and had an average of 9.6 bushels per acre increase in yield over PHG29. PHP55 has better resistance to stalk lodging, better stay green and better seedling vigor than PHG29.

The results in Table 4 compare PHP55 to PHG29 crossed to the same inbred testers. The results show that the two lines differ significantly for a number of traits in hybrid combination. PHP55 offers some key advantages over PHG29. PHP55 hybrids had a 5 bushel per acre yield advantage over the PHG29 hybrids, had better stay green, much higher seedling vigor, and made taller hybrids. PHP55 has very good performance in specific hybrid combinations.

The results in Table 5 compare a PHP55 hybrid to Pioneer® brand 3585. These two hybrids have a parent in common that is not PHP55. Pioneer® brand hybrid 3585 is widely grown in the area where the PHP55 hybrid is adapted. The PHP55 hybrid has a 9% yield advantage, better stalk lodging resistance, and has lower moisture content of the grain at harvest than 3585 which gives the PHP55 hybrid some significant advantages over 3585.

    TABLE 3       PAIRED INBRED COMPARISON DATA INBRED #1 - PHP55 INBRED #2 - PHG29          BU BU BAR BRT EAR EAR EST CLD CLD DRP TIL GDU GDU GRN KER KSZ KSZ      KSZ KSZ  VAR ACR ACR PLT STK HT SZ CNT TST TST EAR LER SHD SLK QUL LB XL      L MR MF YEAR # ABS % MN ABS ABS ABS ABS ABS ABS % MN ABS ABS ABS ABS ABS      ABS ABS ABS ABS ABS        TOTAL SUM 1 77.7 124 94.3 98.4 29.6 6.7 38.3 86.6 102 98.5 1.0 142.7      148.7 5.4 198.3 1.4 23.5 24.3 32.9  2 68.1 110 94.6 99.7 28.5 5.9 40.1      91.3 108 99.6 1.2 139.5 143.9 5.3 206.9 0.1 9.0 26.4 34.6  LOCS 35 35 34      10 37 16 86 14 14 23 35 72 62 29 14 8 8 8 8  DIFF 9.6 14 0.3 1.3 1.1 0.8      1.8 4.7 6 1.2 0.2 3.2 4.8 *10% 8.5 1.3 14.5 2.1 1.8  PROB .001# .003#      .678 .042+  .050* .003# .007# .108 .138 .003# .785 .000# .000# .823 .225      .150 .041+ .714 .733          KSZ KSZ  PLT POL RT TAS TAS TEX TST SCT SDG STA STK STK YLD  VAR S      TIP MST HT SC LDG BLS SZ EAR WT GRN VGR GRN CNT LDG SC YEAR # ABS ABS      ABS ABS ABS ABS ABS ABS ABS ABS ABS ABS ABS ABS ABS ABS        TOTAL SUM 1 15.3 3.0 20.3 75.9 5.7 88.8 8.3 6.1 4.2 53.6 6.8 5.3 4.7      31.0 92.5 7.1  2 24.0 6.3 19.8 69.0 6.8 95.2 8.3 6.8 4.5 56.0 7.3 4.7      3.5 32.3 86.5 6.5  LOCS 8 7 36 38 38 14 3 31 11 35 27 48 32 103 25 27      DIFF 8.8 3.3 0.5 6.8 1.2 6.4 0.0 0.8 0.3 2.4 0.5 0.6 1.2 1.4 5.9 0.6      PROB .048+ .086* .170 .000# .000# .145 .000# .000# .518 .000# .085*      .005# .000# .001# .013+ .015+          ANT  COM COM EAR ECB ECB ECB ECB EYE FUS GLF GOS HC HD NLF SLF SO      VAR ROT CLN RST SMT MLD DPE 1LF 2SC 2IT SPT EAR SPT WLT BLT SMT BLT BLT      RST YEAR # ABS ABS ABS ABS ABS ABS ABS ABS ABS ABS ABS ABS ABS ABS ABS      ABS ABS ABS        TOTAL SUM 1 3.5 3.0 6.0 0.0 6.5 85.9 6.3 4.5 14.2 4.1 11.0 4.0 7.0 5.0      94.9 4.4 4.5 5.0  2 3.0 3.5 6.0 0.0 6.4 95.2 5.8 4.2 15.6 4.8 9.1 3.3      7.0 6.0 95.8 5.3 3.0 4.0  LOCS 1 1 1 1 23 3 24 17 1 4 2 4 1 1 5 4 1 1      DIFF 0.5 0.5 0.0 0.0 0.1 9.4 0.5 0.2 1.4 0.7 2.0 0.8 0.0 1.0 0.9 0.9 1.5      1.0  PROB     .722 .225 .103 .678  .563 .845 .245   .179 .235       *10% SIG      + = 5% SIG      # =  1% SIG

                                      TABLE 4                                      __________________________________________________________________________             8                                                                      Average Inbred by Tester Performance Comparing PHP55 to PHG29 crossed          to the same Inbred Tester and Grown in the Same Experiments. All               Values are Expressed as percent of the experiment mean except Predicted        RM, Selection Index, and Yield (Bu./Ac.).                                      __________________________________________________________________________                      SEL                                                                               BU       GDU STK RT  BAR                                                                               STA TST                                   Inbred                                                                               PRM IND                                                                               ACR                                                                               YLD                                                                               MST                                                                               SHD LDG LDG PLT                                                                               GRN WTA                            __________________________________________________________________________     TOTAL  REPLIC.                                                                              23  23 23 23 23 8   24  2   10 14  23                             MEAN WTS                                                                              PHG29 112 96 113                                                                               97 101                                                                               99  101 77  102                                                                               104 99                             MEAN WTS                                                                              PHP55 112 102                                                                               118                                                                               102                                                                               102                                                                               99  101 62  103                                                                               114 97                                    DIFF      5  5  5  1  1   1   15  1  9   3                              __________________________________________________________________________                               COB                                                                               GRN SDG EST                                                                               PLT                                                                               EAR                                                                               DRP                                                                               BRT                                               Inbred                                                                               SC QUL VGR CNT                                                                               HT HT EAR                                                                               STK                           __________________________________________________________________________                  TOTAL  REPLIC.  6   12  14 12 12 24                                            MEAN WTS                                                                              PHG29    100 89  99 93 95 99                                            MEAN WTS                                                                              PHP55    104 107 99 99 99 99                                                   DIFF.    5   18  0  6  4  1                                __________________________________________________________________________

                                      TABLE 5                                      __________________________________________________________________________     #1 - PHP55 HYBRID                                                              #2 - PIONEER ® BRAND 3585                                                  __________________________________________________________________________                                   BU  BU      GDU STK RT  BAR STA                                VAR     PRM SEL ACR ACR MST SHD LDG LDG PLT GRN                  YEAR    REGION                                                                               #   PRM SHD IND ABS % MN                                                                               *10% ABS                                                                           ABS ABS ABS ABS ABS                  __________________________________________________________________________     TOTAL SUM     1   106 108 114 122.7                                                                              107 18.5                                                                               137.6                                                                              94.4                                                                               98.7                                                                               97.7                                                                               4.6                                2   107 108 100 113.2                                                                              98  19.1                                                                               137.1                                                                              92.2                                                                               99.8                                                                               95.8                                                                               4.3                                LOCS                                                                               4   4   4   27  27  27  10  24  7   8   20                                 DIFF                                                                               2   0   14  9.5 9   0.6 0.6 2.2 1.2 1.9 0.3                                PROB                                                                               .087*                                                                              .719                                                                               .052*                                                                              .004#                                                                              .003#                                                                              .004#                                                                              .312                                                                               .090*                                                                              .155                                                                               .154                                                                               .367                 __________________________________________________________________________                                      TST COB                                                                               GRN SDG EST                                                                               STK                                                                               PLT                                                                               EAR                                                                               DRP                                             VAR WTA SC QUL VGR CNT                                                                               CNT                                                                               HT HT EAR                               YEAR    REGION                                                                               #   ABS ABS                                                                               ABS ABS ABS                                                                               ABS                                                                               ABS                                                                               ABS                                                                               ABS                __________________________________________________________________________                    TOTAL SUM     1   56.2                                                                               5.5                                                                               6.0 5.9 60.4                                                                              47.3                                                                              85.2                                                                              37.2                                                                              99.4                                            2   57.4                                                                               5.0                                                                               5.8 5.9 62.0                                                                              47.4                                                                              83.2                                                                              37.4                                                                              99.6                                            LOCS                                                                               27  1  21  12  20 28 11 11 17                                              DIFF                                                                               1.2 0.5                                                                               0.3 0.0 1.5                                                                               0.1                                                                               2.0                                                                               0.2                                                                               0.2                                             PROB                                                                               .000#  .442                                                                               .881                                                                               .056*                                                                             .800                                                                              .175                                                                              .856                                                                              .437               __________________________________________________________________________       *10% SIG                                                                      + = 5% SIG                                                                     # = 1% SIG                                                               

DEPOSITS

Applicant has made available to the public without restriction a deposit of at least 2500 seeds of inbred PHP55 with the American Type culture Collection (ATCC), Rockville, MD 20852, U.S.A., ATCC Deposit No. 75220. The seeds deposited with the ATCC are taken from the same deposit maintained by Pioneer Hi-Bred International, Inc., 700 Capital Square, 400 Locust Street, Des Moines, Iowa 50309, since prior to the filing date of this application. The deposit of the Inbred corn Line PHPSS without restriction will be maintained at the ATCC Depository, which is a public depository, for a period of 30 years, or five years after the most recent request, or for the effective life of the patent, whichever is longer, and will be replaced if it becomes nonviable during that period. 

What is claimed is:
 1. Inbred corn seed designated PHP55 having ATCC accession No.
 75220. 2. A corn plant produced by the seed of claim
 1. 3. A tissue culture of regenerable cells of the plant of claim
 2. 4. A corn plant regenerated from the tissue culture of claim
 3. 5. An inbred corn plant having all the physiological and morphological characteristics of the plant of claim
 2. 